Overgrown pot in 1 week?

Ok I have tranplanted 4 plants last week around saturday. there were growing in 1 gal pots for about 5 weeks and were starting to be rootbound, so I tranplanted all 4 into 5 gal square buckets filled with fox farmhappy frog potting soil. When I watered them I used 2 tsp of fox farm grow big, tsp of fox farm big bloom, 1 tsp of h202, and 1 drop of superthrive per gallon. I watered each plant one gallon of each mix. Now only 5 days later I noticed alot of roots poking out the bottoms of all 4 plants. Is it possible theyre already out grown the pots in only 5 days? Should I cut back the roots becuase theyre alot of them coming out the holes or or they ok to grow like that? any help apreciated thanks.

Its not likely they outgrew 5 gallon pots. I currently have 5 plants in 2 5 gallon buckets. Its a bit cramped now that they are flowering but they are a little cramped now that I have them lit properly and they are gaining girth. How much soil did you put into the buckets before transplanting? I filled mine halfway and added dirt as they grew untill the buckets were full. So my roots are about 8-10 inches long and nowhere near the bottom yet. As for cutting the roots, I cant say positively that it would hurt them but it doesnt sound like a good idea. I know that when you transplant you are supposed to leave the roots as undisturbed as possible so cutting them doesnt sound like a good plan.